This invention relates generally to a zigzag folding apparatus, and more particularly to such an apparatus having means for decreasing the inertial or body forces brought about during reciprocation to thereby increase the operational speed of the apparatus.
The present apparatus is of the type including an oscillating multi-section guide channel device for delivering a web of paper or other material downwardly from a web conveyer in zigzag folds, the device including upper and lower pivotally interconnected funnels or hoppers for guiding the web therebetween, and drawing rolls for drawing the web downwardly therebetween.
Such a folding apparatus may be operatively connected to a printing machine of the type which produces forms from webs of indeterminant length. After the web, comprising one or more layers, is printed or otherwise processed by such machine it is fed to the zigzag folding apparatus so that the web can be bent along crosswise lines of perforations and disposed in a zigzag stack.
The upper and lower guide funnels of the zigzag folding apparatus serve to better guide the web back and forth so that it can be bent along the crosswise lines of perforations without tenting or bulging out caused by, for example, air turbulances. Such a multi-section guide channel device for the web markedly improves upon guidance of the web to be stacked, as compared to a singlesection guide channel device.
Since the guide funnels are oscillated, and since it is desirable for the web to be folded to move as fast as possible not only through the folding apparatus but also through the machine operatively connected upstream thereof, as for example, the printing press, inertial forces are generated on the parts of the guide channel device which reciprocate. These inertial forces assume a value which limits the running speed of the printing press and, thereby that of the web. As an example, this limitation can be such that the machine connected upstream of the folding apparatus must operate below its maximum speed, because of the folding apparatus.
Folding apparatus of the aforedescribed type having a multi-section guide channel device, are disclosed in German Pat. No. 1,070,010, and in U.S. Pat. Nos. 3,889,940 and 4,045,012. Each such apparatus includes drawing rolls arranged at the downstream end of the multi-section guide channel device for pulling the web downwardly therebetween. Such an arrangement of drawing rolls, however, produces body or inertial forces which undesirably limit the maximum operational speed of the folding apparatus.
Another zigzag folding apparatus, disclosed in German Pat. No. 1,152,301, includes at the downstream end of the guide channel device a double set of drawing rolls associated with endless belts between which the web is drawn downwardly. Such an apparatus also creates inertial forces of such magnitude so as to undesirably limit the capacity of the machine operatively connected upstream of the folding apparatus.